The present invention relates to containers and supports for carrying, containing and/or supporting a work piece or work pieces, including containing and/or supporting a work piece or work pieces during a work piece treatment process and during shipment to and from a treatment process site.
Radiation processing is a widely used method of commercial sterilization. In particular, gamma and electron beam radiation are widely used. Both methods are prominent within the industry for the sterilization of health care products, while electron beam processing holds a large size of the market for raw materials and products such as commercial polymers and gem stones.
Gamma radiation has long been recognized as a safe, cost competitive method for the sterilization of health care products, components and packaging. Gamma radiation, a form of pure energy which is generally characterized by deep penetration of low dose rates, effectively kills micro-organisms throughout a subject product and its packaging with very little temperature effect. Some advantages of gamma radiation are precision dosing, rapid processing, uniform dose distribution, system flexibility and immediate availability of product after processing through dosimetric release. Gamma radiation is a penetrating sterilant. No area of the product, or its components, is left with uncertain sterility after treatment. Packaging remains intact with gamma processing because there is no requirement for pressure and vacuum seals are not stressed. In addition, gamma radiation eliminates the need for permeable packaging materials.
Electron beam (e-beam) radiation is a form of ionizing radiation that can be an effective means of destroying microorganisms. E-beam irradiation, generally characterized by low penetration and high dose rates, is a process by which products are exposed to a concentrated, high current stream of electrons generated by accelerators that produce a beam that is either pulsed or continuous. A work piece or subject material absorbs energy from the electrons as it passes beneath or in front of the electron beam. E-beam irradiation is mostly used in the health care products market for processing of high volume, low value products such as syringes, and for low volume, high value products such as cardio-thoracic devices.
The energy absorbed per unit mass of material processed by radiation is referred to as the absorbed dose and is identified as either a kilo Gray (kGy) or Megarad (Mrad) unit of measure. This absorption alters various chemical and biological bonds, and it is this absorption of energy or dose delivery that destroys the reproductive cells of microorganisms. The accompanying table, labeled Table A, provides a comparison of sterilization methods, including some of the parameters or factors in selecting one of the methods. Commercial e-beam accelerators range in energies from 3 MeV to 12 MeV (million electron volts) and usually operate at a single energy.
Typically, high energy electron beams are needed for sterilization of health care products to achieve penetration of product and packaging. Product density, size and orientation of packaging must be considered when evaluating e-beam sterilization. In general, e-beam irradiation performs best when used on low density, uniform and uniformly packaged products. E-beam sterilization requires the simultaneous control of the beam""s current, scan width and energy, as well as the speed and/or time of exposure, e.g., control of the speed of a conveyor transporting a product through a beam. Speed of the conveyor may be regulated with feed back circuitry from the beam current. If the beam current changes during processing, the conveyor speed correspondingly changes to insure that the delivered dose is held constant.
There are problems, however, currently associated with radiation processing regardless of the type of radiation. First, radiation treatment of work pieces in containers of materials different than that of the work piece may cause the work pieces to have a greater absorbed dose variation. A dissimilar support plate or packaging material can reduce the energy of the penetrating electrons by varying amounts and create a non-uniform dose absorption over the surface area or throughout the thickness of the work piece. In addition, out-gassing from dissimilar support plates and packaging materials causes contamination of the work piece. Finally, work pieces are often manually placed onto and removed from conveyor systems. Handling work pieces in this manner can cause contamination or damage to the work piece.
Accordingly, it would be advantageous to provide a device for use in carrying and/or supporting work pieces to be subjected to e-beam radiation, or other treatments, before, during and after the treatments, wherein the device improves or at least does not adversely impact the efficacy of the e-beam or other treatment.
The present invention is a carrying and support device that will not adversely affect work pieces when subjected to e-beam radiation or other treatments. Specifically, the present invention will reduce or eliminate the amount of out-gassing from dissimilar materials and minimize the absorbed dose variation within the work pieces. The present invention relates to an apparatus for minimizing the amount of out-gassing and absorbed dose variation, as well as a method for sterilizing or otherwise treating a work piece wherein there is little or no out-gassing and a minimum amount of absorbed dose variation.
More specifically, the carrying and support device of the present invention comprises at least one plate which has at least one relieved region for holding a work piece. The plate has a density the same as or very similar to the density of the work piece, so that the plate and work piece together have a substantially uniform density. In addition, in some embodiments the plate can be used for packaging. The plate can be sent to a manufacturer, where the work piece is placed on or into the carrying and support device, without any additional packaging. The manufacturer would then send the entire unit to the treatment site where it is subjected to treatment. The entire unit, now containing a sterilized or otherwise treated work piece, is then sent back to the manufacturer.
The method of the present invention generally includes providing a work piece or work pieces and a support and carrying device having the same or similar density as the work pieces, placing the work pieces on or into the support and carrying device, and subjecting the entire unit to sterilization or other treatment.
Accordingly, an embodiment of the present invention provides a support and carrying device that will not adversely affect work pieces when those work pieces are shipped and/or subjected to commercial sterilization or other treatment.
Another embodiment of the present invention provides a support and carrying device that has a density the same as or very similar to the work pieces to be carried by the support and carrying device.
A further embodiment of the present invention provides a support and carrying device that will not adversely affect work pieces when subjected to treatment and can be used for packaging and shipment.
A still further embodiment of the present invention provides a method for sterilizing or otherwise treating work pieces where the work pieces are not adversely affected by out-gassing or radiation dose variation.
These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings.